The invention relates to a wheel assembly provided with a bracket, a wheel which is mounted in the bracket in such a manner that it can rotate about an axle, a brake member which can move with respect to the wheel and has a brake pin provided with a screw thread, around the brake pin a displaceable brake disc provided with a complementary screw thread, and a locking disc for fixing the position of the brake disc along the screw thread. When the brake pin is moved in the direction of its axis towards the wheel, the brake disc can engage on the wheel in order to brake the wheel.
Wheel assemblies of this type are known and are assembled by the applicant. They are used, for example, in trolleys for catering in aircraft.
Owing to wear on the engagement surface of the wheel mid of the brake disc itself, the braking action may deteriorate over the course of time. To overcome this problem, the position of the brake disc on the brake pin is variable. To displace the brake disc along the brake pin, the locking disc has to be uncoupled, the brake disc has to be moved into the correct position, and finally the locking disc has to be fitted again. According to the prior art, the locking disc is clamped between the brake disc and a locking nut. The locking disc is difficult to remove and fit, since the locking nut, which is situated between the wheel and die bracket, is difficult to reach. Moreover, a tool is required.
One object of the present invention is to make it easier to remove mid fit the locking disc and to enable this to be done without using a tool,
To this end, according to the present invention the locking disc is provided with at least one pawl which is positioned radially with respect to the brake pin and can be displaced substantially in the axial direction of the brake pin. The brake disc is provided with at least one radial slot for accommodating the said pawl in order to prevent the rotation of the brake disc.
Since the rotation of the brake disc is blocked only by the axially projecting pawl, the brake disc can be released by lifting the pawl out of the radial slot. This can be done without using a tool, thus considerably simplifying adjustment of the brake disc.
In a preferred embodiment, the pawl is pressed into the slot by a compression spring. It is preferable for the compression spring to be positioned around the brake pin. It is also preferable for the pawl to be provided with an eyelet which is positioned around the brake pin, the brake pin and the eyelet being flattened on one side in order to prevent rotation of the pawl.
This design uses a small number of components to prevent, in a manner which is robust and requires little maintenance, the pawl from being able to come out of the slot unintentionally, enabling the brake disc to rotate, while continuing to allow simple adjustment of the brake disc without the need for a tool.
In the above preferred embodiments the pawl may also be provided with a lip at its end, which simplifies manual displacement of the pawl in the axial direction,